Polyisocyanurate foam (i.e., PIR board stock) has been widely used to insulate roofs and walls of commercial and industrial buildings for many decades due to its excellent thermal insulation, flame resistance, and mechanical properties. The insulating performance and other performance of polyisocyanurate foams vary based on temperature. For example, FIG. 1 illustrates the insulation performance of a prior polyisocyanurate foam board as a function of temperature. As is apparent, the insulating value of the board peaks at about 65° F., and drops significantly at colder temperatures, and also drops somewhat at higher temperatures.
While polyisocyanurate foams may provide excellent insulation as compared with some other materials, better performance is often desired at lower temperatures. Other methods have been explored for raising the low temperature performance of polyisocyanurate insulation, for example by changing the blowing agent used in making the foam insulation. However, other methods are still desired for improving the low temperature performance of polyisocyanurate foam insulation.